Deportation for expired visas should be automatic. The traveler agreed to depart by date certain. That date has gone by. What else is there to say?
Enforce the terms of the agreement, and put that person on a list (with biometrics) to make sure they never get another visa or consideration for legal immigration.
Do that a few thousand times, and staying on an expired visa will become much less common.
I’ve heard that we get more illegals that way than those sneaking over the border.